View source for Standards that appear together in question clusters

{{DISPLAYTITLE:Which standards appear together in Regents question clusters? {{Titlesub|· analysis of released exams}}}}
Every question on the NYSSLS Regents exams sits inside a question cluster built around one phenomenon, and every question is tagged to one performance expectation (PE). Looking at a released exam, the PEs inside a cluster can seem scrambled: a cluster about balloons jumps from gas behavior to the mole to energy to an engineering standard. This page asks a simple question: '''are PEs assigned to clusters at random, or do certain PEs tend to show up next to each other?'''

The short answer is that they are not random, but the pattern is less "PE A always comes with PE B" and more "each cluster goes deep on one home PE and fills its remaining slots from the same corner of the course." How strong that pattern is, and which specific pairs recur, differs by subject.

'''What was analyzed.''' This analysis is current as of '''Thursday, October 22, 2026''', and uses every administered exam posted on this wiki as of that date. The sample clusters NYSED released before the first exams are '''not''' included, only the real exams. Physics is not analyzed yet because only one exam has been given; a single exam of ten clusters is not enough data to tell a pattern from a coincidence. Physics will be added once more exams have been released.

{| class="wikitable"
! Subject !! Exams included !! Clusters !! Questions
|-
| '''Biology''' || [[June 2025 Life Science: Biology Exam|June 2025]], [[August 2025 Life Science: Biology Exam|August 2025]], [[January 2026 Life Science: Biology Exam|January 2026]], [[June 2026 Life Science: Biology Exam|June 2026]], [[August 2026 Life Science: Biology Exam|August 2026]] || style="text-align:center" | 51 || style="text-align:center" | 235
|-
| '''Earth and Space Science''' || [[June 2025 Earth and Space Science Exam|June 2025]], [[August 2025 Earth and Space Science Exam|August 2025]], [[January 2026 Earth and Space Science Exam|January 2026]], [[June 2026 Earth and Space Science Exam|June 2026]], [[August 2026 Earth and Space Science Exam|August 2026]] || style="text-align:center" | 53 || style="text-align:center" | 250
|-
| '''Chemistry''' || [[June 2026 Chemistry Exam|June 2026]], [[August 2026 Chemistry Exam|August 2026]] || style="text-align:center" | 22 || style="text-align:center" | 98
|-
| '''Physics''' || ''not yet analyzed:'' only one exam ([[June 2026 Physics Exam|June 2026]]) has been given, which is not enough data || style="text-align:center" | — || style="text-align:center" | —
|}

'''How to read the numbers on this page.''' For each subject, the PE labels were shuffled across all of that subject's question slots 50,000 times, keeping every cluster the same size it really is. That shows what the exams would look like if PEs were handed out to clusters at random. Wherever this page says "expected by chance," it means the average from those shuffles. When the real exams differ from the shuffled ones by a wide margin, that is a pattern worth knowing about; when they do not, an apparent pattern is probably noise. The method and its limits are described at the bottom of the page.

== How the three subjects compare ==

{| class="wikitable" style="width:100%"
! !! Biology !! Earth and Space Science !! Chemistry
|-
| '''Clusters where one PE is assessed two or more times''' || 24 of 51 (47%)<br><small>chance: 14 (28%)</small> || 39 of 53 (74%)<br><small>chance: 19 (36%)</small> || 17 of 22 (77%)<br><small>chance: 8 (35%)</small>
|-
| '''Repeated-PE questions placed back to back''' || no more than chance<br><small>8 pairs; chance: 7</small> || yes, strongly<br><small>45 pairs; chance: 10</small> || yes<br><small>12 pairs; chance: 4</small>
|-
| '''Share of PE pairs within a cluster that come from the same course-map unit''' || 30%<br><small>chance: 13%</small> || 35%<br><small>chance: 15%</small> || 30%<br><small>chance: 24%</small>
|-
| '''Hard separation between content areas''' || strong: molecular biology and genetics vs. ecology || near-absolute: space vs. Earth || not visible yet
|-
| '''Specific PE pairs that beat chance after correcting for the number of pairs tested''' || none (several suggestive) || one ([[HS-ESS1-1]] + [[HS-ESS1-3]]) || none
|}

Three things stand out.

* '''Earth and Space Science clusters are the most predictable.''' Nearly three-quarters have an "anchor" PE that is assessed two to five times, usually in consecutive questions, and the space-science PEs (ESS1-1, ESS1-2, ESS1-3, ESS1-4, ESS1-7) essentially never share a cluster with an Earth-science PE.
* '''Biology clusters are the most mixed, but they are mixed within four content worlds''' (genetics and cells; physiology, metabolism and carbon; population ecology; evolution and behavior). Biology's strongest pairs are concept chains rather than topic repeats, for example DNA and protein synthesis paired with sources of genetic variation, or body systems paired with homeostasis. When a Biology cluster repeats a PE, the repeated questions are ''not'' placed next to each other.
* '''Chemistry already shows the anchor pattern after only two exams''', but two exams is not enough to say which PEs pair with which. That part of the Chemistry analysis should be read as a list of things to watch, not rules.

== Biology ==

Five exams, 51 clusters, 235 questions. Of the 30 Biology PEs, 29 have appeared at least once; [[HS-ETS1-4]] (simulations) has not yet been assessed.

=== Four content worlds ===

When you look at which PEs actually share clusters, they sort themselves into four groups. These groups were found from the exam data itself (see the method section), and they mostly line up with the course map, with one notable difference: on the exam, [[HS-LS1-1]] (DNA and protein synthesis) belongs with the genetics PEs, not with its course-map neighbors [[HS-LS1-2]] and [[HS-LS1-3]] (body systems and homeostasis), which travel with metabolism and the carbon cycle instead.

{| class="wikitable"
! Group !! PEs that travel together !! Engineering PE that attaches to this group
|-
| '''Genetics and cells''' || [[HS-LS1-1]], [[HS-LS1-4]], [[HS-LS1-8]], [[HS-LS3-1]], [[HS-LS3-2]], [[HS-LS3-3]] || [[HS-ETS1-2]]
|-
| '''Physiology, metabolism and carbon''' || [[HS-LS1-2]], [[HS-LS1-3]], [[HS-LS1-5]], [[HS-LS1-6]], [[HS-LS1-7]], [[HS-LS2-3]], [[HS-LS2-5]], [[HS-ESS2-6]], [[HS-ESS2-7]] || [[HS-ETS1-1]]
|-
| '''Population ecology''' || [[HS-LS2-1]], [[HS-LS2-2]], [[HS-LS2-4]], [[HS-LS2-6]], [[HS-LS2-7]] || [[HS-ETS1-3]]
|-
| '''Evolution and behavior''' || [[HS-LS2-8]], [[HS-LS4-1]], [[HS-LS4-2]], [[HS-LS4-3]], [[HS-LS4-4]], [[HS-LS4-5]] || —
|}

The wall between the molecular side and the ecological side is strong but not absolute. Only 12 of the 51 clusters contain both a molecular/genetics PE (the LS1 and LS3 standards) and an ecology PE (the LS2 standards plus ESS2-6 and ESS2-7); at random, about 36 clusters would. [[HS-LS1-1]] is the clearest case: it appears in 11 clusters and has never once shared one with [[HS-LS2-1]], [[HS-LS2-2]], [[HS-LS2-6]], [[HS-LS4-4]] or [[HS-ETS1-3]], each of which chance would have paired with it two or more times. Evolution clusters, on the other hand, draw freely from both sides: [[HS-LS3-1]] (genes and traits) shows up in evolution storylines as often as in genetics ones.

=== PEs that show up together ===

{| class="wikitable"
! Pair of PEs !! Clusters containing both !! Expected by chance !! Notes
|-
| [[HS-LS1-1]] DNA and Protein Synthesis + [[HS-LS3-2]] Sources of Genetic Variation
| style="text-align:center" | 7
| style="text-align:center" | 2.1
| 7 of the 10 clusters that assess LS3-2 also assess LS1-1; the strongest pair in Biology
|-
| [[HS-LS1-1]] DNA and Protein Synthesis + [[HS-LS3-1]] DNA, Genes, and Traits
| style="text-align:center" | 6
| style="text-align:center" | 2.3
| DNA structure paired with how genes determine traits
|-
| [[HS-LS1-4]] Mitosis and Differentiation + [[HS-LS3-2]] Sources of Genetic Variation
| style="text-align:center" | 5
| style="text-align:center" | 1.3
| mitosis and meiosis in the same storyline
|-
| [[HS-LS1-2]] Body Systems and Functions + [[HS-LS1-3]] Homeostasis and Feedback
| style="text-align:center" | 5
| style="text-align:center" | 1.7
| 5 of the 6 clusters that assess LS1-3 also assess LS1-2
|-
| [[HS-LS2-1]] Carrying Capacity and Ecosystems + [[HS-LS2-2]] Biodiversity and Populations
| style="text-align:center" | 5
| style="text-align:center" | 1.7
| population and biodiversity clusters
|-
| [[HS-LS2-1]] Carrying Capacity and Ecosystems + [[HS-LS2-6]] Ecosystem Stability and Change
| style="text-align:center" | 5
| style="text-align:center" | 1.8
| population and ecosystem-change clusters
|-
| [[HS-LS2-6]] Ecosystem Stability and Change + [[HS-ETS1-3]] Evaluating Solutions and Trade-offs
| style="text-align:center" | 5
| style="text-align:center" | 1.8
| engineering questions attach to ecology clusters, not genetics clusters
|-
| [[HS-LS3-1]] DNA, Genes, and Traits + [[HS-LS3-2]] Sources of Genetic Variation
| style="text-align:center" | 5
| style="text-align:center" | 1.8
| 
|-
| [[HS-ESS2-6]] Carbon Cycling + [[HS-LS2-5]] The Carbon Cycle
| style="text-align:center" | 4
| style="text-align:center" | 0.8
| the two carbon-cycle PEs are assessed together in 4 of the 5 clusters that assess LS2-5
|-
| [[HS-LS2-8]] Group Behavior and Survival + [[HS-LS4-2]] Mechanisms of Natural Selection
| style="text-align:center" | 4
| style="text-align:center" | 1.3
| group behavior framed as a product of natural selection
|}

A caution about this table. Biology has 406 possible pairs of PEs, and 18 of them beat chance at the usual statistical threshold, which is about the number (20) that chance alone would produce. No single Biology pair passes a formal correction for that. The pairs listed above are the ones that are consistent across the five exams and make biological sense as a storyline, so treat them as likely but not proven.

=== Anchors and repeats ===

24 of the 51 clusters assess one PE two or three times, against about 14 expected by chance. Unlike the other two subjects, Biology does not place the repeated questions next to each other: 8 back-to-back same-PE pairs, against 7 by chance. The PEs most often doubled within a cluster are [[HS-LS1-1]] and [[HS-LS1-3]] (three clusters each), then [[HS-LS1-8]] (doubled in two of its three clusters), [[HS-LS4-1]], [[HS-LS4-2]] and [[HS-LS4-4]] (two clusters each).

=== Coverage ===

The most-assessed Biology PE is [[HS-LS4-2]] (mechanisms of natural selection), with 16 questions in 14 of the 51 clusters, followed by [[HS-LS1-1]] with 14 questions. At the other end, [[HS-ESS2-7]] has 2 questions in five exams, [[HS-LS1-6]] has 3, and [[HS-LS1-5]] (photosynthesis), [[HS-ETS1-1]] and [[HS-ETS1-2]] have 4 each.

{| class="wikitable mw-collapsible mw-collapsed" style="width:100%; text-align:center"
|+ Biology: how often each PE was assessed across the five exams (click to expand)
! Performance expectation !! Questions !! Clusters it appears in !! Clusters where it was assessed 2+ times
|-
| style="text-align:left" | [[HS-LS4-2]] Mechanisms of Natural Selection || 16 || 14 || 2
|-
| style="text-align:left" | [[HS-LS1-1]] DNA and Protein Synthesis || 14 || 11 || 3
|-
| style="text-align:left" | [[HS-LS1-2]] Body Systems and Functions || 12 || 11 || 1
|-
| style="text-align:left" | [[HS-LS2-6]] Ecosystem Stability and Change || 12 || 10 || 1
|-
| style="text-align:left" | [[HS-LS3-1]] DNA, Genes, and Traits || 12 || 11 || 1
|-
| style="text-align:left" | [[HS-LS4-1]] Evidence for Evolution || 12 || 8 || 2
|-
| style="text-align:left" | [[HS-LS4-4]] Natural Selection and Adaptation || 12 || 10 || 2
|-
| style="text-align:left" | [[HS-ETS1-3]] Evaluating Solutions and Trade-offs || 11 || 10 || 1
|-
| style="text-align:left" | [[HS-LS2-1]] Carrying Capacity and Ecosystems || 11 || 10 || 1
|-
| style="text-align:left" | [[HS-LS2-2]] Biodiversity and Populations || 11 || 10 || 1
|-
| style="text-align:left" | [[HS-LS3-2]] Sources of Genetic Variation || 11 || 10 || 1
|-
| style="text-align:left" | [[HS-LS1-3]] Homeostasis and Feedback || 10 || 6 || 3
|-
| style="text-align:left" | [[HS-ESS2-6]] Carbon Cycling || 9 || 8 || 1
|-
| style="text-align:left" | [[HS-LS1-4]] Mitosis and Differentiation || 8 || 7 || 1
|-
| style="text-align:left" | [[HS-LS2-3]] Matter and Energy in Ecosystems || 7 || 6 || 1
|-
| style="text-align:left" | [[HS-LS2-7]] Human Impacts on Biodiversity || 7 || 6 || 1
|-
| style="text-align:left" | [[HS-LS2-5]] The Carbon Cycle || 6 || 5 || 1
|-
| style="text-align:left" | [[HS-LS2-8]] Group Behavior and Survival || 6 || 6 || 0
|-
| style="text-align:left" | [[HS-LS4-5]] Environmental Change and Evolution || 6 || 5 || 1
|-
| style="text-align:left" | [[HS-LS1-7]] Cellular Respiration || 5 || 5 || 0
|-
| style="text-align:left" | [[HS-LS1-8]] Human Reproduction and Development || 5 || 3 || 2
|-
| style="text-align:left" | [[HS-LS2-4]] Energy Flow and Matter Cycling || 5 || 5 || 0
|-
| style="text-align:left" | [[HS-LS3-3]] Genetics and Probability || 5 || 5 || 0
|-
| style="text-align:left" | [[HS-LS4-3]] Natural Selection and Traits || 5 || 4 || 1
|-
| style="text-align:left" | [[HS-ETS1-1]] Analyzing Global Challenges || 4 || 4 || 0
|-
| style="text-align:left" | [[HS-ETS1-2]] Breaking Down Complex Problems || 4 || 4 || 0
|-
| style="text-align:left" | [[HS-LS1-5]] Photosynthesis || 4 || 4 || 0
|-
| style="text-align:left" | [[HS-LS1-6]] Synthesis of Biomolecules || 3 || 2 || 1
|-
| style="text-align:left" | [[HS-ESS2-7]] Coevolution of Earth and Life || 2 || 2 || 0
|}

[[File:Biology PE co-occurrence heatmap.png|thumb|center|900px|Biology: how many clusters contain each pair of PEs, across the five exams. Darker cells are pairs that showed up together more often. The dashed diagonal shows how many clusters assessed that PE two or more times. PEs are ordered by the four groups above.]]

== Earth and Space Science ==

Five exams, 53 clusters, 250 questions. All 25 Earth and Space Science PEs have appeared at least once.

=== The wall between space and Earth ===

Only one of the 53 clusters (''The Origin of Our Solar System'', June 2025) contains both a Space Systems PE ([[HS-ESS1-1]], [[HS-ESS1-2]], [[HS-ESS1-3]], [[HS-ESS1-4]], [[HS-ESS1-7]]) and any ESS2 or ESS3 PE. At random, about 39 clusters would mix the two, and in 20,000 shuffles the number never dropped below 28. In practice: when a cluster opens with a star, a planet, an orbit, an eclipse or the Big Bang, expect every question in it to be an ESS1 standard (occasionally plus [[HS-ETS1-3]]). [[HS-ESS1-4]] (orbital motion and gravity) appears in 10 clusters and has never shared one with [[HS-ESS2-2]], the most common PE on the exam, where chance would give five.

[[HS-ESS1-6]] (formation and early history of Earth) and [[HS-ESS2-7]] (coevolution of Earth and life) are the bridge: they sit with the astronomy PEs in solar-system and moon clusters and with tectonics and surface-process PEs in early-Earth and fossil clusters.

=== Three groups ===

{| class="wikitable"
! Group !! PEs that travel together
|-
| '''Space and early Earth''' || [[HS-ESS1-1]], [[HS-ESS1-2]], [[HS-ESS1-3]], [[HS-ESS1-4]], [[HS-ESS1-7]], plus the bridge PEs [[HS-ESS1-6]] and [[HS-ESS2-7]]
|-
| '''Solid Earth, water and resources''' || [[HS-ESS1-5]], [[HS-ESS2-1]], [[HS-ESS2-3]], [[HS-ESS2-5]], [[HS-ESS2-6]], [[HS-ESS3-1]], [[HS-ESS3-2]], [[HS-ESS3-4]], [[HS-ESS3-6]]
|-
| '''Climate, weather and feedbacks''' || [[HS-ESS2-2]], [[HS-ESS2-4]], [[HS-ESS2-8]], [[HS-ESS3-3]], [[HS-ESS3-5]]
|}

Compared with the course map, the exam splits the "Earth's Systems" unit three ways: [[HS-ESS2-2]] (feedbacks) goes with the climate PEs, [[HS-ESS2-3]] and [[HS-ESS2-5]] (convection, water) go with tectonics and surface processes, and [[HS-ESS2-7]] goes with early Earth. The "Human Sustainability" unit is also split, with [[HS-ESS3-3]] landing with the climate group.

=== Deep, narrow clusters ===

Earth and Space Science clusters go deep on one PE more than any other subject's. 39 of the 53 clusters assess one PE two or more times (chance: 19). There are 68 "repeat" questions beyond the first question for each PE (chance: 22), and 45 of them are placed immediately after another question on the same PE (chance: 10). Nine clusters are built from only one or two PEs: ''Horse Latitudes'' (August 2025) and ''Conditions of a Polar Vortex Event'' (June 2026) are five questions each on [[HS-ESS2-8]] alone, and ''Energy in the Sun'' (August 2025) is four questions on [[HS-ESS1-1]] plus one on [[HS-ESS1-3]].

[[HS-ESS1-4]] (orbital motion and gravity) is the most anchor-prone PE in any of the three subjects: 19 questions in 10 clusters, doubled or tripled in 8 of them.

=== PEs that show up together ===

{| class="wikitable"
! Pair of PEs !! Clusters containing both !! Expected by chance !! Notes
|-
| [[HS-ESS1-1]] The Sun and Its Energy + [[HS-ESS1-3]] Stellar Nucleosynthesis
| style="text-align:center" | 6
| style="text-align:center" | 1.3
| 6 of the 7 clusters that assess ESS1-1 also assess ESS1-3; the only pair in any subject that survives correction for the number of pairs tested
|-
| [[HS-ESS1-2]] Big Bang Theory + [[HS-ESS1-3]] Stellar Nucleosynthesis
| style="text-align:center" | 5
| style="text-align:center" | 1.3
| 5 of the 6 clusters that assess ESS1-2
|-
| [[HS-ESS1-4]] Orbital Motion and Gravity + [[HS-ESS1-7]] Cycles of the Sun, Earth, and Moon
| style="text-align:center" | 6
| style="text-align:center" | 2.7
| moon, eclipse, transit and supermoon clusters
|-
| [[HS-ESS2-1]] Earth's Surface Processes + [[HS-ESS2-3]] Thermal Convection in Earth
| style="text-align:center" | 6
| style="text-align:center" | 2.6
| hotspot, volcano and plate-tectonics clusters
|-
| [[HS-ESS3-1]] Natural Resources, Hazards, and Human Activity + [[HS-ESS3-2]] Resource Use and Conservation
| style="text-align:center" | 5
| style="text-align:center" | 1.8
| mining and resource clusters
|-
| [[HS-ESS2-2]] Feedbacks in Earth's Systems + [[HS-ESS3-5]] Climate Change Forecasting
| style="text-align:center" | 5
| style="text-align:center" | 2.3
| climate-model clusters
|-
| [[HS-ESS2-5]] Water and Earth's Surface Processes + [[HS-ESS3-4]] Reducing Human Impact on Natural Systems
| style="text-align:center" | 4
| style="text-align:center" | 1.3
| dam and river clusters
|-
| [[HS-ESS2-4]] Energy Flow and Climate Change + [[HS-ESS3-5]] Climate Change Forecasting
| style="text-align:center" | 3
| style="text-align:center" | 0.8
| 
|}

Two PEs act as connectors that attach to almost any Earth phenomenon: [[HS-ESS2-2]] (feedbacks; 22 questions in 18 clusters) and [[HS-ESS3-1]] (natural resources, hazards and human activity; 17 questions in 16 clusters). Engineering is nearly absent from this exam: 10 of the 250 questions are ETS standards, and [[HS-ETS1-2]] and [[HS-ETS1-4]] have appeared once each.

=== Coverage ===

The most-assessed PEs are [[HS-ESS2-2]] (22 questions), [[HS-ESS2-1]] (20) and [[HS-ESS1-4]] (19). [[HS-ESS1-5]] (plate tectonics and crustal ages) has only 4 questions in five exams even though tectonics is a frequent cluster theme; those clusters are coded to [[HS-ESS2-1]] and [[HS-ESS2-3]] instead. [[HS-ESS2-6]] (carbon cycling) has 5.

{| class="wikitable mw-collapsible mw-collapsed" style="width:100%; text-align:center"
|+ Earth and Space Science: how often each PE was assessed across the five exams (click to expand)
! Performance expectation !! Questions !! Clusters it appears in !! Clusters where it was assessed 2+ times
|-
| style="text-align:left" | [[HS-ESS2-2]] Feedbacks in Earth's Systems || 22 || 18 || 4
|-
| style="text-align:left" | [[HS-ESS2-1]] Earth's Surface Processes || 20 || 16 || 4
|-
| style="text-align:left" | [[HS-ESS1-4]] Orbital Motion and Gravity || 19 || 10 || 8
|-
| style="text-align:left" | [[HS-ESS3-1]] Natural Resources, Hazards, and Human Activity || 17 || 16 || 1
|-
| style="text-align:left" | [[HS-ESS2-8]] Air Masses and Weather || 16 || 7 || 3
|-
| style="text-align:left" | [[HS-ESS1-6]] Formation and Early History of Earth || 14 || 9 || 3
|-
| style="text-align:left" | [[HS-ESS1-1]] The Sun and Its Energy || 12 || 7 || 3
|-
| style="text-align:left" | [[HS-ESS1-2]] Big Bang Theory || 12 || 6 || 4
|-
| style="text-align:left" | [[HS-ESS1-7]] Cycles of the Sun, Earth, and Moon || 11 || 7 || 4
|-
| style="text-align:left" | [[HS-ESS2-5]] Water and Earth's Surface Processes || 11 || 8 || 3
|-
| style="text-align:left" | [[HS-ESS3-6]] Human Impact on Earth Systems || 11 || 8 || 2
|-
| style="text-align:left" | [[HS-ESS2-3]] Thermal Convection in Earth || 10 || 7 || 3
|-
| style="text-align:left" | [[HS-ESS3-4]] Reducing Human Impact on Natural Systems || 9 || 8 || 1
|-
| style="text-align:left" | [[HS-ESS1-3]] Stellar Nucleosynthesis || 8 || 7 || 1
|-
| style="text-align:left" | [[HS-ESS2-7]] Coevolution of Earth and Life || 8 || 5 || 2
|-
| style="text-align:left" | [[HS-ESS3-2]] Resource Use and Conservation || 8 || 8 || 0
|-
| style="text-align:left" | [[HS-ESS3-3]] Resource Management and Sustainability || 8 || 6 || 2
|-
| style="text-align:left" | [[HS-ESS3-5]] Climate Change Forecasting || 8 || 5 || 2
|-
| style="text-align:left" | [[HS-ESS2-4]] Energy Flow and Climate Change || 7 || 6 || 1
|-
| style="text-align:left" | [[HS-ETS1-3]] Evaluating Solutions and Trade-offs || 6 || 6 || 0
|-
| style="text-align:left" | [[HS-ESS2-6]] Carbon Cycling || 5 || 5 || 0
|-
| style="text-align:left" | [[HS-ESS1-5]] Plate Tectonics and Crustal Ages || 4 || 3 || 1
|-
| style="text-align:left" | [[HS-ETS1-1]] Analyzing Global Challenges || 2 || 2 || 0
|-
| style="text-align:left" | [[HS-ETS1-2]] Breaking Down Complex Problems || 1 || 1 || 0
|-
| style="text-align:left" | [[HS-ETS1-4]] Modeling Solutions with Simulations || 1 || 1 || 0
|}

[[File:Earth and Space Science PE co-occurrence heatmap.png|thumb|center|900px|Earth and Space Science: how many clusters contain each pair of PEs, across the five exams. The empty block in the upper right is the wall between space-science and Earth-science PEs.]]

== Chemistry ==

Two exams, 22 clusters, 98 questions. Of the 21 Chemistry PEs, 20 have appeared; [[HS-ETS1-4]] has not. With only two exams, the Chemistry results are the least settled of the three subjects, and the pair-level findings in particular should be read as hypotheses to check against the next exams.

=== Anchors ===

The clearest Chemistry pattern is the same one seen in Earth and Space Science: 17 of the 22 clusters assess one PE two or three times, where chance would give about 8, and those repeated questions are usually consecutive (12 back-to-back pairs; chance: 4). The anchor is always the phenomenon's home topic.

{| class="wikitable"
! Anchor PE !! Clusters where it was assessed two or three times
|-
| [[HS-PS1-5]] Reaction rates || [[Questions:Equilibria in the Blood|Equilibria in the Blood]] and [[Questions:Clock Reaction|Clock Reaction]] (June 2026), [[Questions:Catalytic Converter in Cars|Catalytic Converter in Cars]] (August 2026)
|-
| [[HS-PS1-11]] Acids and bases || [[Questions:Chemistry of Beverages|Chemistry of Beverages]] (June 2026), [[Questions:Pool Water Chemistry|Pool Water Chemistry]] (August 2026)
|-
| [[HS-PS1-3]] Intermolecular forces || [[Questions:The Accidental Development of Breathable, Waterproof Fabric|Breathable, Waterproof Fabric]] (June 2026), [[Questions:Get a Whiff of That!|Get a Whiff of That!]] (August 2026)
|-
| [[HS-PS3-1]] Energy transfer || [[Questions:Urban Heat Islands|Urban Heat Islands]] (June 2026), [[Questions:Go With the Flow|Go With the Flow]] (August 2026; three questions)
|-
| [[HS-PS1-9]] Gas behavior || [[Questions:Balloon Arches|Balloon Arches]] (June 2026), [[Questions:Parade of Balloons|Parade of Balloons]] (August 2026); these are its only two appearances
|-
| [[HS-PS4-4]] Electromagnetic radiation || [[Questions:The Great American Solar Eclipse|The Great American Solar Eclipse]] and [[Questions:The ABCs of Ultraviolet Radiation|The ABCs of Ultraviolet Radiation]] (August 2026)
|-
| [[HS-PS1-8]] Nuclear processes || [[Questions:Electricity Generation in New York State|Electricity Generation in New York State]] (August 2026; three questions)
|-
| [[HS-PS1-1]], [[HS-PS2-6]], [[HS-PS1-10]], [[HS-PS1-12]] || one cluster each: [[Questions:Semiconductors|Semiconductors]], [[Questions:Chip Bag: PFAS vs PLA Plastics|Chip Bag: PFAS vs PLA Plastics]], [[Questions:Get a Whiff of That!|Get a Whiff of That!]], [[Questions:All About Aluminum|All About Aluminum]]
|}

=== The other questions come from the same neighborhood ===

Using the course-map units on the [[Chemistry]] standards page, 30% of the PE pairs found within a cluster come from the same unit, against 24% by chance: a real but modest tilt. The tilt is clearer if the PEs are grouped by content instead: a materials block ([[HS-PS1-1]], [[HS-PS1-2]], [[HS-PS1-3]], [[HS-PS2-6]]) and an aqueous-chemistry block ([[HS-PS1-10]], [[HS-PS1-11]], [[HS-PS1-5]], [[HS-PS1-6]], [[HS-PS1-12]]) are visible as darker squares along the diagonal of the heatmap below. Whether those blocks hold up, and whether a space-versus-Earth style wall develops, will become clear with more exams.

=== PEs that show up together (so far) ===

{| class="wikitable"
! Pair of PEs !! Clusters containing both !! Expected by chance !! Notes
|-
| [[HS-PS1-10]] Solutions + [[HS-PS1-7]] Conservation of Mass
| style="text-align:center" | 4
| style="text-align:center" | 1.9
| Chemistry of Beverages, Chip Bag, The Fruit Industry, The ABCs of Ultraviolet Radiation
|-
| [[HS-PS1-2]] Chemical Reactions + [[HS-PS2-6]] Structure and Function of Materials
| style="text-align:center" | 3
| style="text-align:center" | 1.1
| All About Aluminum, Semiconductors, Safe Transport of Drinking Water
|-
| [[HS-PS1-10]] Solutions + [[HS-PS1-11]] Acids and Bases
| style="text-align:center" | 3
| style="text-align:center" | 1.7
| Chemistry of Beverages, Clock Reaction, The Fruit Industry
|-
| [[HS-PS1-10]] Solutions + [[HS-PS1-5]] Reaction Rates
| style="text-align:center" | 3
| style="text-align:center" | 2.1
| Chemistry of Beverages, Clock Reaction, Get a Whiff of That!
|-
| [[HS-LS1-5]] Photosynthesis + [[HS-PS1-11]] Acids and Bases
| style="text-align:center" | 2
| style="text-align:center" | 0.5
| both clusters that assess photosynthesis (Photosynthetic Pathways, The Fruit Industry) also assess acids and bases
|-
| [[HS-PS4-4]] Electromagnetic Radiation and Matter + [[HS-ETS1-2]] Breaking Down Complex Problems
| style="text-align:center" | 2
| style="text-align:center" | 0.6
| Urban Heat Islands, The Great American Solar Eclipse
|}

None of these pairs beats chance once you account for the 190 possible pairs being tested: finding one pair at the usual threshold out of 190 is exactly what chance produces. Two exams is simply too little data for pair-level conclusions. By the fifth or sixth exam this question will be answerable, as it is for Biology and Earth and Space Science.

=== Bolt-on PEs ===

[[HS-PS1-7]] (conservation of mass and the mole) is the most interesting non-pattern in Chemistry. It appeared in 8 of the 22 clusters, always exactly once, and was never a cluster's anchor. It is the add-on calculation question that gets attached to whatever the phenomenon is. The engineering PEs behave the same way (8 questions in 8 different clusters, always single), as does [[HS-PS1-2]] (5 clusters, always single).

=== Coverage ===

[[HS-PS1-5]] (reaction rates) is the most-assessed Chemistry PE so far with 9 questions, followed by [[HS-PS1-7]] and [[HS-PS1-10]] with 8 each. [[HS-PS1-4]] (energy and chemical reactions) appeared once in 98 questions, [[HS-PS1-6]] (equilibrium) twice, [[HS-ETS1-1]] once, and [[HS-ETS1-4]] not at all.

{| class="wikitable mw-collapsible mw-collapsed" style="width:100%; text-align:center"
|+ Chemistry: how often each PE was assessed (June 2026 and August 2026 exams; click to expand)
! Performance expectation !! Questions !! Clusters it appears in !! Clusters where it was assessed 2+ times
|-
| style="text-align:left" | [[HS-PS1-5]] Reaction Rates || 9 || 6 || 3
|-
| style="text-align:left" | [[HS-PS1-10]] Solutions || 8 || 7 || 1
|-
| style="text-align:left" | [[HS-PS1-7]] Conservation of Mass || 8 || 8 || 0
|-
| style="text-align:left" | [[HS-PS1-11]] Acids and Bases || 7 || 5 || 2
|-
| style="text-align:left" | [[HS-PS1-8]] Nuclear Processes || 7 || 5 || 1
|-
| style="text-align:left" | [[HS-PS2-6]] Structure and Function of Materials || 7 || 6 || 1
|-
| style="text-align:left" | [[HS-PS3-1]] Energy Transfer || 7 || 4 || 2
|-
| style="text-align:left" | [[HS-PS4-4]] Electromagnetic Radiation and Matter || 6 || 4 || 2
|-
| style="text-align:left" | [[HS-PS1-1]] Periodic Table || 5 || 4 || 1
|-
| style="text-align:left" | [[HS-PS1-2]] Chemical Reactions || 5 || 5 || 0
|-
| style="text-align:left" | [[HS-PS1-3]] Intermolecular Forces || 5 || 3 || 2
|-
| style="text-align:left" | [[HS-ETS1-3]] Evaluating Solutions and Trade-offs || 4 || 4 || 0
|-
| style="text-align:left" | [[HS-PS1-12]] Electron Transfer || 4 || 3 || 1
|-
| style="text-align:left" | [[HS-PS1-9]] Gas Behavior || 4 || 2 || 2
|-
| style="text-align:left" | [[HS-ETS1-2]] Breaking Down Complex Problems || 3 || 3 || 0
|-
| style="text-align:left" | [[HS-PS3-5]] Forces and Fields || 3 || 3 || 0
|-
| style="text-align:left" | [[HS-LS1-5]] Photosynthesis || 2 || 2 || 0
|-
| style="text-align:left" | [[HS-PS1-6]] Chemical Equilibrium || 2 || 2 || 0
|-
| style="text-align:left" | [[HS-ETS1-1]] Analyzing Global Challenges || 1 || 1 || 0
|-
| style="text-align:left" | [[HS-PS1-4]] Energy and Chemical Reactions || 1 || 1 || 0
|}

[[File:Chemistry PE co-occurrence heatmap.png|thumb|center|900px|Chemistry: how many clusters contain each pair of PEs, across the June 2026 and August 2026 exams. With only two exams, the groups here are content groupings chosen for display rather than groups found from the data.]]

== Method and caveats ==

* '''Data.''' The PE tag for every question comes from this wiki's exam pages, which list the standard NYSED assigns to each question. Each question is counted under exactly one PE. Sample clusters are excluded.
* '''"Expected by chance."''' For each subject, the PE labels were randomly reshuffled across all of that subject's question slots 50,000 times with cluster sizes held fixed, so each shuffle has exactly the same number of questions per PE as the real exams, just distributed differently among clusters. Every "expected" figure on this page is the average over those shuffles.
* '''Counting pairs.''' "Clusters containing both" counts a cluster once if both PEs appear in it at least once, regardless of how many questions each PE got.
* '''Multiple comparisons.''' Biology has 406 possible PE pairs, Earth and Space Science 300, and Chemistry 190. With that many pairs, some will beat chance by accident, so each subject's pair list was also checked with a false-discovery-rate correction (Benjamini–Hochberg). Only one pair in any subject, [[HS-ESS1-1]] + [[HS-ESS1-3]], passes that correction. The other pairs listed are reported because they are large, consistent across exams and sensible, not because they are statistically proven.
* '''The groups.''' For Biology and Earth and Space Science, the content groups were found by community detection (the Louvain method) on the network of which PEs share clusters. They describe what the exams have done so far; they are not a rule NYSED has published. For Chemistry, there is not enough data for that, so the heatmap groups are a content grouping chosen for display.
* '''Course-map units''' are the headings used on this wiki's [[Biology]], [[Earth and Space Science]] and [[Chemistry]] standards pages.
* '''This page will be updated''' as each new exam is released. The Chemistry section in particular should change substantially once four or five exams are available, and Physics will be added at that point too.

{{Pagecontributors}}
<metadesc>Which NYSSLS performance expectations appear together in question clusters on the released Biology, Earth and Space Science and Chemistry Regents exams: anchors, content groups and recurring PE pairs, as of October 22, 2026.</metadesc>